Experimental investigation on the dynamic behavior of 3D printed CF-PEKK composite under cyclic uniaxial compression

The main goal of the present work was to investigate the effect of infill density on dynamic behavior of 3D printed parts. The short carbon-fibre-reinforced PolyEtherKetoneKetone composites (CF-PEKK) was selected as material which has an excellent mechanical, physical, thermal and energy absorbing performance. It's employed widely in a vast range of industries due to their ultra-low density, multi-functionality and ability to undergo large deformations at low loads. For this purpose, a procedure for characterizing the dynamic behavior of this material fabricated with Fused Filament Fabrication (FFF) is presented in this research. Three infill densities (20%, 50% and 100%) were experimentally compressed for different impact pressures (1,4 bar; 1,7 bar; 2 bar and 2,4 bar) using Split Hopkinson Pressure Bar (SHPB). A FASTCAM high-speed camera was positioned in front of the SHPB test set-up to capture the dynamic deformation processes. The special attention is also given to examine the dynamic response of 3D printed CF-PEKK (100% infill density) subjected to repeated impacts. The obtained results proved that the low density and high-density infills were more cost-effective when compared to solid samples. The repeated impact drastically changed the dynamic behavior of the material compared to standard impact. With increasing the number of impact loading to the final failure, the dynamic parameters (i.e dynamic modulus, maximum stress ...etc.) decreased remarkably and the material suffered catastrophic cumulated damage.